Global trade in grains will drop 4.9 percent in the 2012-13 marketing year, according to the U.S. Department of Agriculture. Forward freight agreements, handled by brokers and used to bet on future costs, anticipate a fourth-quarter rate of $9,117 a day, 17 percent less than now, Baltic Exchange data show.

Shares of Eagle Bulk Shipping Inc., the largest U.S. operator of the vessels, will slump 30 percent in the next 12 months, according to the average of six analyst estimates compiled by Bloomberg.

Corn and soybean prices rose to records this month as U.S. farmers plowed under ruined fields and heat waves across Europe wilted crops from Italy to Russia. The fourth quarter is usually the most important for Supramaxes hauling grain as it coincides with the Northern Hemisphere’s harvests. The period generated the best average returns in four of the past six years.

“Those droughts are very bad news for the shipping industry,” said Marc Pauchet, an analyst at London-based ACM Shipping Group Plc, the U.K.’s third-largest publicly traded shipbroker. “It seems grain production is going to be worse than even we had anticipated.”

Read further, including in-depth analysis, in Bloomberg's report: "Grain Cargoes Seen Slowing Most in 19 Years on Drought: Freight," by Rob Sheridan.